Expose RTT and throughput estimates from Cronet

components/cronet/android/java/src/org/chromium/net/impl/CronetUrlRequestContext.java

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.net.impl;
 
 import android.content.Context;
 import android.os.Build;
 import android.os.ConditionVariable;
 import android.os.Handler;
 import android.os.Looper;
 import android.os.Process;
 import android.util.Log;
 
 import org.chromium.base.ObserverList;
 import org.chromium.base.VisibleForTesting;
 import org.chromium.base.annotations.CalledByNative;
 import org.chromium.base.annotations.JNINamespace;
 import org.chromium.base.annotations.NativeClassQualifiedName;
 import org.chromium.base.annotations.UsedByReflection;
 import org.chromium.net.BidirectionalStream;
 import org.chromium.net.CronetEngine;
 import org.chromium.net.EffectiveConnectionType;
 import org.chromium.net.NetworkQualityRttListener;
 import org.chromium.net.NetworkQualityThroughputListener;
 import org.chromium.net.RequestFinishedInfo;
+import org.chromium.net.RttThroughputValues;
 import org.chromium.net.UrlRequest;
 import org.chromium.net.urlconnection.CronetHttpURLConnection;
 import org.chromium.net.urlconnection.CronetURLStreamHandlerFactory;
 
 import java.net.Proxy;
 import java.net.URL;
 import java.net.URLConnection;
 import java.net.URLStreamHandlerFactory;
 import java.util.ArrayList;
 import java.util.Collection;
@@ skipping 50 matching lines @@
      */
     private final Object mFinishedListenerLock = new Object();
 
     /**
      * Current effective connection type as computed by the network quality
      * estimator.
      */
     @GuardedBy("mNetworkQualityLock")
     private int mEffectiveConnectionType = EffectiveConnectionType.TYPE_UNKNOWN;
 
+    /**
+     * Current estimate of the HTTP RTT (in milliseconds) computed by the
+     * network quality estimator.
+     */
+    @GuardedBy("mNetworkQualityLock")
+    private int mHttpRttMs = RttThroughputValues.INVALID_RTT_THROUGHPUT_VALUE;
+
+    /**
+     * Current estimate of the transport RTT (in milliseconds) computed by the
+     * network quality estimator.
+     */
+    @GuardedBy("mNetworkQualityLock")
+    private int mTransportRttMs = RttThroughputValues.INVALID_RTT_THROUGHPUT_VALUE;
+
+    /**
+     * Current estimate of the downstream throughput (in kilobits per second)
+     * computed by the network quality estimator.
+     */
+    @GuardedBy("mNetworkQualityLock")
+    private int mDownstreamThroughputKbps = RttThroughputValues.INVALID_RTT_THROUGHPUT_VALUE;
+
     @GuardedBy("mNetworkQualityLock")
     private final ObserverList<NetworkQualityRttListener> mRttListenerList =
             new ObserverList<NetworkQualityRttListener>();
 
     @GuardedBy("mNetworkQualityLock")
     private final ObserverList<NetworkQualityThroughputListener> mThroughputListenerList =
             new ObserverList<NetworkQualityThroughputListener>();
 
     @GuardedBy("mFinishedListenerLock")
     private final List<RequestFinishedInfo.Listener> mFinishedListenerList =
@@ skipping 220 matching lines @@
             throw new IllegalStateException("Network quality estimator must be enabled");
         }
         synchronized (mNetworkQualityLock) {
             synchronized (mLock) {
                 checkHaveAdapter();
             }
             return mEffectiveConnectionType;
         }
     }
 
+    @Override
+    public int getHttpRttMs() {
+        if (!mNetworkQualityEstimatorEnabled) {
+            throw new IllegalStateException("Network quality estimator must be enabled");
+        }
+        synchronized (mNetworkQualityLock) {
+            synchronized (mLock) {
+                checkHaveAdapter();

[xunjieli, 2016/10/18 21:52:00]

Why do we need to checkHaveAdapter() here? Can we just return the result
directly? If the adapter isn't initialized or torn down, we will return invalid,
which seems reasonable.

[tbansal1, 2016/10/19 21:51:39]

I suppose checking the adapter helps in catching errors. Just like it is checked
in other methods.

[xunjieli, 2016/10/19 23:32:27]

In other places (except getEffectiveConnectionType()), checkHaveAdapter() makes
sure we are not calling into native code with a null object. Since we are not
calling into native code, there isn't a reason to incur the synchonization cost.
I'd suggest removing 
synchronized(mLock) {
   checkHaveAdapter();
}

[tbansal1, 2016/10/20 00:29:18]

Done.

+            }
+            return mHttpRttMs;
+        }
+    }
+
+    @Override
+    public int getTransportRttMs() {
+        if (!mNetworkQualityEstimatorEnabled) {
+            throw new IllegalStateException("Network quality estimator must be enabled");
+        }
+        synchronized (mNetworkQualityLock) {
+            synchronized (mLock) {
+                checkHaveAdapter();
+            }
+            return mTransportRttMs;
+        }
+    }
+
+    @Override
+    public int getDownstreamThroughputKbps() {
+        if (!mNetworkQualityEstimatorEnabled) {
+            throw new IllegalStateException("Network quality estimator must be enabled");
+        }
+        synchronized (mNetworkQualityLock) {
+            synchronized (mLock) {
+                checkHaveAdapter();
+            }
+            return mDownstreamThroughputKbps;
+        }
+    }
+
     @VisibleForTesting
     @Override
     public void configureNetworkQualityEstimatorForTesting(
             boolean useLocalHostRequests, boolean useSmallerResponses) {
         if (!mNetworkQualityEstimatorEnabled) {
             throw new IllegalStateException("Network quality estimator must be enabled");
         }
         synchronized (mLock) {
             checkHaveAdapter();
             nativeConfigureNetworkQualityEstimatorForTesting(
@@ skipping 173 matching lines @@
     private void onEffectiveConnectionTypeChanged(int effectiveConnectionType) {
         synchronized (mNetworkQualityLock) {
             // Convert the enum returned by the network quality estimator to an enum of type
             // EffectiveConnectionType.
             mEffectiveConnectionType = effectiveConnectionType;
         }
     }
 
     @SuppressWarnings("unused")
     @CalledByNative
+    private void onRTTOrThroughputEstimatesComputed(
+            final int httpRttMs, final int transportRttMs, final int downstreamThroughputKbps) {
+        synchronized (mNetworkQualityLock) {
+            mHttpRttMs = httpRttMs;
+            mTransportRttMs = transportRttMs;
+            mDownstreamThroughputKbps = downstreamThroughputKbps;
+        }
+    }
+
+    @SuppressWarnings("unused")
+    @CalledByNative
     private void onRttObservation(final int rttMs, final long whenMs, final int source) {
         synchronized (mNetworkQualityLock) {
             for (final NetworkQualityRttListener listener : mRttListenerList) {
                 Runnable task = new Runnable() {
                     @Override
                     public void run() {
                         listener.onRttObservation(rttMs, whenMs, source);
                     }
                 };
                 postObservationTaskToExecutor(listener.getExecutor(), task);
@@ skipping 98 matching lines @@
     @NativeClassQualifiedName("CronetURLRequestContextAdapter")
     private native void nativeProvideRTTObservations(long nativePtr, boolean should);
 
     @NativeClassQualifiedName("CronetURLRequestContextAdapter")
     private native void nativeProvideThroughputObservations(long nativePtr, boolean should);
 
     public boolean isNetworkThread(Thread thread) {
         return thread == mNetworkThread;
     }
 }